Friction clutch, especially for motor vehicles

ABSTRACT

Friction clutch, especially for motor vehicles, includes a housing, a pair of torque-transmitting friction discs disposed in the housing, a respective pressure plate located adjacent each of the friction discs, lever means operatively connected to the pressure plates and actuable for displacing the pressure plates in axial direction of the clutch, the pressure plates having friction surfaces facing away from one another and being formed with annular seats on respective surfaces thereof facing toward one another, a plate spring disposed between the pressure plates and engaging the annular seats, the housing being securable to a flywheel and being formed with a reaction surface engageable by one of the friction discs, the flywheel having a reaction surface engageable by the other of the friction discs, and means for rotationally entraining the pressure plates, both of the friction discs having respective hubs mountable on a single driven member for transmitting torque thereto.

United States Patent 1191 Maucher Dec. 18, 11973 [54] FRICTION CLUTCH,ESPECIALLY FOR 3,224,531 12/1965 Thompson 192/70 X MOTOR VEHICLES3,424,288 l/l969 Sink l92/70.29 X

[75] Inventor: Paul Maucher, Sasbach, Germany FOREIGN PATENTS ORAPPLICATIONS [73] Assigneez Luk Lameuen und Kupphmgsbau 585,566 11/1958Italy 192/99 A GmbH, Buhl (Baden), Germany I Primary Examiner-Allan D.Herrmann [22] Fled: 1971 Attorney-Curt M. Avery et a1. [21] App]. No.:118,364

[57] ABSTRACT Foreign Application Priority Data Friction clutch,especially for motor vehicles, includes Feb. 24, 1970 Germany P 20 ()8424.6 a housing, a pair of torque-transmitting friction discs Dec. 18,1970 Germany P 20 62 410.6 disposed in the housing, a respectivepressure plate 10- I cated adjacent each of the friction discs, levermeans [52] U.S. Cl 192/70, l92/70.2, 192/70.29, operatively connected tothe pressure plates and actul92/70.3, l92/89 B, 192/99 A able fordisplacing the pressure plates in axial direc- [51] Int. Cl. F1611 13/44tion of the clutch, the pressure plates having friction [58] Field ofSearch 192/70.29, 70.2, surfaces facing away from one another and beingl92/70.3, 89 B, 99 A, 70, 70.18 formed with annular seats on respectivesurfaces thereof facing toward one another, a plate spring dis- [56]References Cited posed between the pressure plates and engaging theUNITED STATES PATENTS annular seats, the housing being securable to 213,590,968 7 1971 Binder 192/99 A flywheel and being f .with reactionSurface 3,245,499 4/1966 Kershner 192/70 X gageable by one of thefr'cuon dscsr the flywheel 2,211,192 8/1940 Wolfram 192/70.18 ing areaction Surface ehgageable y the other of the 3061'062 10/1962 5 m og70 3 friction discs, and means for rotationally entraining 2,387,03910/1945 Parrett.,. 188/714 the pressure plates, both of the frictiondiscs having 2,436,817 3/1948 Miller 192/99 A X respective hubsmountable on a single driven member A X for transmitting torque thereto3,212,611 10/1965 Ruoff et al.... l92/70.3 X 3,215,233 11/1965 Smith etal 192/70.3 X 8 Claims, 12 Drawing Figures PATENTEU HEB 1 8 m5 SHEET 10F6 ll m PAIENTEDBEEWIHH 37791353 sum 2 or e Fig. 2

PATENTED DEC 18 1975 SHEET l- UF 6 QATENTEODEC 18 1975 3,779,353

mgmgnna: 18 1575 3379.353

SHEETBOF 6 l FRICTION CLUTCH, ESPECIALLY FOR MOTOR VEHICLES Theinvention relates to friction clutch, especially for motor vehicles.

For the purpose of transmitting the usually very high power in heavytruck constructions, double disc clutches are often used which, againstexpectations, do not transmit double the power that is transmitted bycorresponding single disc clutches of the same dimensions and with thesame friction diameter. Attempts were therefore made to produce optimalconditions by using single disc clutches of suitably larger dimensions.However, this requires an enormous diameter for the clutch ball, andconstruction difficulties result therefrom because the entire motortransmission unit must be located at a sufficiently high level in orderto ensure the required ground clearance. In the case of motors which aremounted beneath the floor this necessitates a very large spacerequirement and because of that the useful space is lost.

In double disc clutches that have become known, for example, in GermanPatent No. 738,516, there are located in sequence within a pot-shapedflywheel whose base is constructed as a counter pressure surface, anaxially displaceable friction disc, an axially displaceable pressureplate with the two friction surfaces, a second axially displaceablefriction disc, as well as a second axially displaceable pressure plate.The lastmentioned pressure plate is subjected to the biasing action ofhelical compression springs and the pressure from these springs istransmitted from there to the second friction disc andfrom the latter tothe first pressure plate and then further to the first friction discwhich is then pressed with its friction covering against the counterpressure surface of the pot-shaped flywheel.

Clutches of this type have a number of disadvantages which set narrowlimits on their load capacity and thereby on the possibilities of theuse or operation thereof. Thus, for example, the transmittable power isconsiderably lower on the corresponding load value of two single discclutches because, due to the simultaneous frictional force of bothfriction discs which is applied to the one pressure plate locatedtherebetween, very high temperatures are produced which moreover cannotbe dissipated especially because of the type of construction of theclutch. In addition, the compressive force at the first clutch disc issmaller due to the friction in the axial guides, whereby thetransmission moment of at least this clutch disc becomes smallerresulting in an increased wear of the second clutch disc with respect tothe first clutch disc. Furthermore, the removal and the engagement ofthe pressure plates takes place differently with the friction disc andunder different pressure ratios so that an irregular, excessive wearoccurs.

Clutches have become known of the type, for example, disclosed in GermanPublished Application No. 1,294,223, which have proved their value bothin thermal respect as well as with respect to their ruggedness under themost extreme operating conditions and, in fact, are double frictionclutches for tractors, equipment carriers and similar motor vehicles.These clutches are formed of a respective clutch member for a variablegear transmission and for an auxiliary driv-e wherein the clutch memberscan be separated or connected in series and transmit a torque separatelyto a transmission and to an auxiliary drive, for example, a

feeder shaft. Two friction discs are provided for transmitting torquerespectively having their own pressure plates displaceable axiallythrough a lever system, the pressure plates provided with frictionsurfaces facing away from one another-being engageable by a plate springloated therebetween and abutting annular seats on the pressure plates,as well as a housing which is securable to the flywheel and is providedwith a reaction or counteracting surface engageable with the one of thefriction discs, the flywheel serving as a reaction or counteractingsurface for the other friction disc, as well as means for rotationallyentraining the pressure plates.

It is an object of the invention to provide a double disc clutch whichis capable of transmitting double the power, for equal radialdimensions, as single disc clutches of the same order of magnitude.

It is a further object of the invention that the thermal load capacityshould also be maintained with respect to the heretofore employed singleclutches which, for example, occur very frequently under difficultstarting-up operations in hilly terrain and which often extend over longperiods of time.

It is another object of the invention to provide such a double discclutch having an especially great durability, simple construction andhigh functional reliability.

It is still a further object of the invention to provide an improvementover the heretofore known clutches of this general type which, for thesame axial dimensions, is capable to transmit double the powertransmittable by single disc clutches.

With the foregoing and other objects in view, there is provided inaccordance with the invention, a friction clutch comprising a housing, apair of torquetransmitting friction discs disposed in the housing, arespective pressure plate located adjacent each of the friction discs,lever means operatively connected to the pressure plates and actuablefor displacing the pressure plates in axial direction of the clutch, thepressure plates having friction surfaces facing away from one anotherand being formed with annular seats on respective surfaces thereoffacing toward one another, a plate spring disposed between the pressureplates and engaging the annular seats, the housing being securable to aflywheel and being formed with a reaction surface engageable by one ofthe friction discs, the flywheel having a reaction surface engageable bythe other of the friction discs, and means for rotationally entrainingthe pressure plates, both of the friction fiscs having respective hubsmountable on a single drive member for transmitting torque thereto.

Further in accordance with the invention, the single drive member, forexample, the transmission shaft, can be constructed as a step shaft, sothat each hub can be seated on a profile of different diameter and/ordifferent shape. In by far most cases, it is advantageous in accordancewith the invention for both hubs to have similar profiles, because then,the construction of the conventionally toothed transmission shaft ismarkedly simplified.

In accordance with another feature of the invention, the lever meanscomprises respective lever systems for each of the pressure plates, thelever systems being actuable substantially in parallel by a commonmember for lifting both of the pressure plates, the lever means beingadapted to effect a substantially simultaneously instituted oppositelydirected displacement of the pressure plates. For this, one of the leversystems is formed of a two-arm lever pivotally mounted on the housingand having a connecting means for pulling one of the pressure plates inlifting direction while the second lever system is a one-arm lever alsopivotally mounted on the housing. The one-arm lever system has at leastone compression member for the purpose of disengaging the clutch, thecompression member serving to transform the pivoting movement of thislever system into an axial lifting movement of the pressure plate.

In accordance with another feature of the invention, the common memberis an annular compression member articulatingly connected to at leastthe levers of one of the lever systems, and has a side thereof facingthe levers of the one lever system and formed with profiled sections ona radially inner region of the levers, for example, at the dome thereofand is biased advantageously by resilient means. These resilient meansserve simultaneously for returning the compression member at the levers,for resiliently biasing the compression member against the levers andfor formand forcelockingly bracing the levers with the disengagingmembers thereof, namely the tension and compression members.

The levers of the other system abut profiled sections of the compressionmember, in accordance with an added feature of the invention. In manycases, it is sufficient if these levers engage smooth surface portionsof, for example, a circularly formed compression member.

In accordance with another feature of the invention, the means forrotationally entraining the pressure plates comprise leaf spring memberssecurable, on the one hand, to the pressure plates and, on the otherhand, to at least one of the housing and the flywheel, for example byrivets or screws.

In accordance with other features of the invention, the leaf springs areformed of U-shaped loops and are attached at given points to thepressure plates on the one hand, and to at least the housing or theflywheel or both, on the other hand, the leaf-springs extending atvarious angles from the points of attachment on the pressure plates tothe points of attachment on at least the housing or the flywheel orboth. The loop section of the U-shaped loops can either face toward theconnecting points at the pressure plate or at the housing.

In accordance with an additional feature of the invention, the points ofattachment on the pressure plates are either staggered radially orcircumferentially or both.

In accordance with other features of the invention, the single-armedlevers form a knife-edge bearing with a respective bearing memberprovided at the housing. The bearing members are formed as bearingstands and have a wall projecting substantially'in axial direction ofthe clutch and extending in circumferential or tangential direction, thewall having a given profiling, and the one-arm levers having acorresponding counterprofiling abutting the given profiling. Thereby,the levers can be secured at the bearing block from movement incircumferential, axial and radial directions.

In accordance with a further feature of the invention, both the bearingstand as well as the levers can be formed of sheet metal profilemembers.

In accordance with yet another feature of the invention, the one-armlevers have, radially inwardly of the bearing stand, a contact memberengageable with one end of a compression pin slideably supported in aguide formed in the housing and having an end facing away from thecontact member and abutting an absorption means of the one pressureplate.

In accordance with still other features of the invention, the contactmember is adjustable in the level thereof in order to be able to adjustthe instant of disengagement of this one pressure plate, in order toaccommodate for wear, and in order to assure a uniform adjustment of allthree levers of this system. With this, the contact member is providedwith a threaded portion threadedly secured in a threaded bushing, whichhas a flange abutting a side of the one-arm lever facing the housing, acounteracting nut being located at the other side of the one-arm lever.By this means, the contact member is simultaneously adjustable in level,and a force-locking connection between the contact member, the threadedbushing and the levers is attainable.

In accordance with a concomitant feature of the invention the means forrotationally entraining the pressure plates include leaf springssecurable on the one hand to the housing and on the other hand to thepressure plates, the bearing stands and at least one of the leaf springsbeing securable to the housing by a common fastening member.

In accordance with another feature of the invention, the double-armlevers include a radially outwardly extending lever connected to atension member, the tension member being, in form, oparativelyengageable with one of the pressure plates, the double-arm levers havingbearings constructed as rocker bearings.

The invention also includes the feature of a pin secured to the housingand extending substantially parallel to the clutch axis, the double-armlevers enclasping the pin. The pin is pormed with a knurled portionlocated in press-fitting engagement within a bore formed in the housing.In such case, the two-arm lever can be a sheet-metal profile member.

In accordance with a further feature of the invention thedouble-arm-lever is formed with an oval opening extending in radialdirection, the pin being received within the oval opening which, asviewed in circumferential direction, is fitted to the diameter of thepin and forms with a radially inner region thereof an abutment for thepin.

In accordance with additional features of the invention, thedouble-arm-lever is formed with an oval opening extending in radialdirection, the pin being received within the oval opening which, asviewed in circumferential direction, is fitted to the diameter of thepin and forms with a radially inner region thereof an abutment for thepin.

In accordance with additional features of the invention, a plate membersurrounds the pin, and the doublearm lever abuts the plate member, whichmay be of arched construction. The double-arm lever has a flat surfaceengageable with the plate member, and the latter may be formed ofwear-resistant material.

In accordance with other features of the invention, an anti-torsiondevice is located between the doublearm lever and the plate member.

In accordance with a different feature of the invention, the rockerbearings are formed by a member having a substantially sphericalsurface, the double-arm lever having a corresponding counter profilingengaging the spherical surface.

In accordance with added features of the invention, an arm extends fromthe double-arm lever in axial direction of the clutch and abuts thehousing. A plate-like member of wear resistant material is located onthe housing, the arm extending from the double-arm lever being inengagement with the plate-like member.

According to another feature of the invention, a bearing member issecured to the housing and has a wall projecting substantially in axialdirection of the clutch and extensible in circumferential direction ofthe clutch, the bearing member having at least one profiling, thedouble-arm lever having a corresponding counter-profiling of the bearingmember, and forming with the the bearing member a knife-edge bearing.Furthermore, either the double-arm lever or the bearing member or bothare sheet metal profile members.

In accordance with another feature of the invention,

there is provided means for guiding movement of the pivotable single anddouble-arm levers in pivoting direction thereof, the guiding means beinglocated radially inwardly of the contact member and comprising a pinsecured to the housing. The guiding means is also located radiallyinwardly of the .plate member. Stop means are located in a radiallyinner region of the single and double arm levers for limiting pivotalmovement of the pivotally mounted single and double arm levers indirection opposite to the housing. The stop means also comprise a pinsecured to the housing. The pins are also provided with an annularshoulderforming member engageable by the double-arm lever. The guidingpin is formed with knurl portion pressfitted in a bore formed in thehousing. The stop pin is of similar construction and is similarlypress-fitted in a bore formed in the housing.

In accordance with an additional feature of the'invention there isprovided a bar spring engaging the lever means for bracing the same, thebar spring having a first force arm engaging the lever means, a secondforce arm engaging the housing and spring windings between the forcearms thereof, the second force arm being in engagement with the levermeans at an angle of inclination for forming a resultant force thatcauses the windings of of the bar spring to abut the housing in alloperating positions of the lever means at the housing.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin friction clutch, especially for motor vehicles, it is neverthelessnot intended to be limited to the details shown, since variousmodifications and structural changes may be made therein withoutdeparting from the spirit of the invention and within the scope andrange of equivalents of the claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawing, in

which:

FIG. 1 is a sectional view of the friction clutch constructed inaccordance with the invention;

FIG. 2 is a much-enlarged fragmentary view of FIG.

FIGS. 3 and 4 are upper and lower half sectional views, respectively, ofanother embodiment of the friction clutch;

FIGS. 5, 6 and 7 are respective elevational plan and sectional views ofa detail of FIG. 4;

FIG. 8 is a front elevational view of another detail of FIG, 4;

FIG. 9 is a fragmentary view in section of a modification of the clutchof FIG. 3;

FIG. I0 is a sectional view of FIG. 9 taken along the line X X in thedirection of the arrows;

FIGS. ill and 12 are fragmentary sectional views similar to FIG. 9 ofother modifications of the friction clutch of the invention.

Referring now to the drawings and first, particularly to FIGS. l and 2thereof, there is shown a friction clutch, especially for motorvehicles, constructed in accordance with the invention, having twofriction discs 1 and 2 for torque transmission and a respective axiallydisplaceable pressure plate 3 and 4 for the friction discs 1 and 2. Bothpressure plates 3 and 4 are provided with friction surfaces 3 and 4,respectively, facing away from one another. A plate spring 5 is disposedbetween the pressure plates 3 and 4 and is prestressed so as to abutprojecting seats 6 and 7 of both pressure plates 3 and 4, respectively,in a conventional manner, and thereby press both pressure plates 3 and 4against the friction discs 1 and 2, respectively.

A housing 8 of the clutch is provided with a counterpressure or reactionsurface 8' for the friction disc 2 and is securable by screws 9 to aflywheel 10. The flywheel 10 has a friction surface 10' which is formedas a counterpressure or reaction surface for the friction disc 1.

The friction discs 1 and 2 are provided with respective hubs 11 and 12which, in the embodiment of FIG. 1, have a similar profile fortransmitting torque to a single driven member, namely a transmissionshaft 13.

To lift both pressure plates 3 and 4, there is provided for each of thepressure plates, its own lever system 14 and 15, advantageously havingrespectively three levers. The levers of the lever system 14 are formedas double-armed levers and are swingably mounted at 16 on the housing 8.A tie rod 18 is articulatingly connected through a radially furtheroutwardly disposed lever arm by means of a pin or bolt 17. Thus, bymeans of the levers of the lever system 14, the pressure plate 3 isliftable from the friction disc 1 in direction of the arrow 19.

The levers of the lever system 15 are formed of single-arm levers thatare pivotable about a pin 20 secured to the housing 8. Radially furtherinwardly a compression member 22 is articulatingly secured by a pivot21, the compression member 22 abutting an adjusting screw 23 which isthreadedly secured to the pressure plate 4. Thus, by means of the leversof the lever system 15, a disengaging movement of the pressure plate 4is effected in direction of the arrow 24.

Actuation of the friction clutch of the invention is effected throughboth lever systems 14 and 15 in parallel by means of a common member,namely a compression member 25, it being especially advantageous thatthe actuation of both lever systems be effected at least substantiallysimultaneously because then the least possible wear occurs at thefriction discs 1 and 2.

The levers l4 and 15 and adjustable by means of the tie rod 18 and theadjusting screw 23, respectively, so that the lift or disengagement ofthe pressure plates 3 and 4 occurs simultaneously.

The compression member 25 is swung or shifted by a non-illustrateddisengaging lever in direction of the arrow 26,which effects an oppositelift of the pressure plates 3 and 4, by means of the lever systems 14and 15, in direction of the arrows l9 and 24. The compression member 25is formed with profiled sections 27 facing the levers of the leversystem, and is biased by resilient means, namely by bar springs 29 sothat the profiled sections 27 engage rounded heads 28 of the leversystem 14, the spring 29 serving simultaneously for retaining thecompression member 25, for resiliently pressing the same against thelevers and as a prestress within the disengaging system 14, 18.

For the levers of the lever system 15, the compression member may alsobe provided with profiled sections within which the rounded heads 31 ofthe levers may lie, however, in the embodiment illustrated in FIG. 1,the heads 31 of the lever system 15 abut a flat surface portion of thecompression member 25. The prestress within the lever system 15 isproduced through the bar springs 32.

As seen in FIG. 2, leaf spring members 33 are provided for rotationallylockingly entraining the pressure plates 3 and 4. The leaf springmembers 33, on the one hand, are riveted to radially projecting cams 34and 35 of the pressure plates 4 and 3 respectively, and on the otherhand, are threadedly secured by a bolt 36 to the housing 8. In manycases, it may be advantageous, if the leaf spring members 33 are formedat least of one U- shaped bent loop, the bent connecting piece betweenthe legs of such a U-loop being shown by dot-dash lines in FIG. 2.

In many instances, it may also be especially desirable for the points ofattachment to the pressure plates to be mutually offset radially and/orcircumferentially, because assembly can then be markedly simplified.

It can be seen that friction clutches according to FIGS. 1 and 2 of theinvention in the instant application, have a number of significantadvantages over the heretofore known double disc clutches. Thus, forexample, by using for each friction disc its own pressure plate, theheat absorption capacity and the heat transmission are markedly improvedover that for the heretofore known clutches of this general type. Theheat transfer is further improved by the fact that the projecting seats6 and 7 operate like turbine blades or buckets and produce a cooling airflow sweeping radially past the pressure plates 3 and 4 as well as theplate spring 5. This cooling air flow may be further intensified byproviding the friction discs 2 either with air inlet openings or withblade or bucket-like air-moving means for an axially admitted air flow.Especially because of the exceptionally favorable construction of thefriction clutch according to the invention, it is possible, with respectto thermal problems, to transfer actually double the produced heat thanis possible for single disc clutches of the same order of magnitude.Also, the use of a single plate spring for applying pressure to bothclutch discs affords significant advantages which are not attainablewith the heretofore known two-disc clutches which have used helicalcompression springs heretofore. Thus, for example, by suitablyconstructing the plate spring, assurance can be provided that over theentire path of wear of the friction linings, the pressure will remainsubstantially constant and, moreover, a substantially uniformapplication or course of pressure will prevail along the disengagingpath.

Furthermore, there is assured-by the plate. spring and the constructionthat the pressure plates respectively, are placed with the same force onboth clutch discs,

thereby avoiding non-uniform wear of the friction linings and markedlyincreasing the longevity or durability of the clutch of the invention.

The forced lifting of the pressure plates 3 and 4 from the clutch discs1 and 2, respectively, through the two lever systems 14 and 15 assures atrouble-free clutch disengaging operation, it being especiallyadvantageous if the opposite lift of the two pressure plates 3 and 4 iseffected substantially simultaneously and is in the same order ofmagnitude. The trouble-free clutch disengaging operation has as a resultthat, in the clutch disengaged condition, both clutch discs 1 and 2 canrotate freely with reliability so that wear of the friction lining isavoided in this condition and, moreover, synchronization in thetransmission is not additionally stressed by the drag moment, as couldnot be reliably avoided with the heretofore used friction clutches.

In addition, the use of a common compression member 25 for both leversystems 14 and 15 and the articulating connection of the securingthereof, as well as the retention of the compression member 25 at theends of the levers of the one lever system 14 afford considerableadvantage. For example, due to the use of only one compression member, amarked economy is achieved. Furthermore, due to this construction, it ispossible by the sole use of restoring springs at one set of levers tobias the compression member against thelevers of both lever systems 14and 15 in order to prestress them both.

The embodiment of the invention shown in FIGS. 3 and 4 is a double discclutch formed of a first clutch member A and a second clutch member B,the clutch member A being provided with a friction disc 41 while theclutch member B has a friction disc 42, both of the clutch members A andB including respective hubs 41a and 42a that are fixed against radialmovement though axially displaceable on a transmission shaft G.Furthermore, the clutch member A includes a pressure plate 43, and theclutch member B, a pressure 44, which are engageable with frictionsurfaces at the discs 41 and 42, respectively. The pressure plates 43and 44 are subjected to the biasing action of a plate spring 45 whichabuts radially outwardly on cams or bead-like prominences 46 of thepressure plate 43 and further radially inwardly on bead-like prominencesor cams 47 formed on the pressure plate 44, from which both pressureplates 43 and 44 receive their spring loading or stress- Both clutchmembers A and B are mounted in a common housing 48 which is providedwith a counterpressure or reaction surface 49 for the clutch disc 41. Aflywheel S, to which the housing 48 is bolted by nonillustrated means ina conventional manner, provides a counterpressure surface 50 for theclutch member B.

In a conventionally known manner, leaf springs 51 are employed foreffecting torque transmission between the housing 48 and both pressureplates 43 and 44.

To lift the pressure plates, there are distributed over the periphery ofthe housing 48, two systems or groups A and B of three levers each thatare swingably or pivotablly mounted at the housing 48. The levers of thesystem A are single-armed and are so disposed that when they are pivotedin direction of the arrow a, they exert a pressure on the pressure plate43 and lift the latter from the friction disc 41.

The lever system A forms through its radially outer lever arm A"aknife-edge bearing with a bearing member 52. The latter bearing memberis illustrated in greater detail in FIGS. to 7, and the lever system Ais also shown more clearly in FIG. 8.

The bearing member 52, which is formed as a bearing stand in theembodiment of FIGS. 3 and 4, has a wall 53 which projects substantiallyin axial direction of the clutch of the invention, and extends incircumferential or tangential direction. This bearing stand 52 isprovided with profiles 54 against which the lever system A, formed withcorresponding counter-profiles, abuts. Thereby, the levers of the systemA are secured against displacement at the bearing stand 52 incircumferential, axial and radial directions.

By means of a bolt 56, both the bearing stand 52, as

well as the leaf springs 51 are secured to the housing Radially inwardthe bearing stand 52, the lever system A is provided with a contactmember 57 i.e. a worm screw in the embodiment of FIGS. 3 and 4, whichlies on one end of a compression pin 58. The compression pin 58 isslidingly mounted in a guide 59 of the housing 48, and has another endby which it is seated on the absorption means of the pressure plate 43,namely a cam 60.

The contact member 57 is adjustable in level by means of a threadedbushing 61 formed with a flange 62 and by means of a counteracting nut63. The lever system A is clamped between the flange 62 and thecounteracting nut 63.

The system B of double-armed levers is swung or pivoted in direction ofthe arrow b for the purpose of clutch disengagement, and thereby exertstension on the pressure plate 44 through a tension member 64, which isgripped by the lever system B, the pressure plate 44 being accordinglylifted from the disc 42 against the biasing force of the spring 45.

The tension members 64 are shown in the embodiment of FIGS. 3 and 4 asbolts which extend through a bore 65 of a cam 66 formed on the pressureplate 44. A nut 67, threaded on thle tension members 64, abuts thesurface 68 of the cam Z66. In the illustrated embodiment of FIGS. 3 and4, both the bore 65 and the surface 68 serve as absorption drarticulating means for the bolt 64 functioning as clutch disengagingmeans and the nut 67.

The levers of the system B have a seesaw or rocker bearing i.e. theyhave a substantially spherical or balllike surface 69 abutting asubstantially flat, hardened disc 70 and can effect swinging movementson this disc 70. The lever system B is formed with an oval bore 72through which a pin 71 extends. The oval bore 72 in peripheral directionconforms to the diameter of the pin 71. The radially inner region of theoval opening 72 abuts the pin 71 so that the lever system B isadditionally secured against the action of centrifugal force. The pins71 are provided with a knurled region 71a and this region of the pins isdriven into a bore 73 formed in the housing 48.

Both the lever systems A and B are formed with a bore in the radiallyinner region thereof through which a respective pin 74 extends, the pin74 having a knurled region which is driven or press-fitted into arespective bore 75 formed in the housing 48. The pins 74 serve togetherwith the bores 76 and 77 in the levers A and B as a guide for the leversin the swinging or pivoting direction thereof.

Snap rings 78 are provided on the pins 74 and serve as stop means forlimiting the swinging movement of the levers in direction away from thehousing 48.

The seesaw bearing for the lever system B, as shown in FIGS. 9 to 12,can also however be formed in other ways. For example, in FIG. 9, thelever system B has a flat roll-off surface 78' and forms the seesawbearing with a platelet or small disc 79 having an arched construction.It is expedient to provide a safety device against torsion between thelever system B and the platelet 79, in accordance with FIG. 10 which isa cross section-a1 view of FIG. 9 taken along the lines X X. Thisanti-torsion safety device is constructed by fonning the platelet 79with contours 80 which substantially conform to the squared-off regionB" and is at least there overlapped by the regions B.

FIG. 11 shows a seesaw bearing for the lever system B wherein the latteris provided with profiles 81 with which it is superposed oncounter-profiles 82 of a bearing member 83 which is, in turn, secured tothe housing 48. The profiles 81 and 82 may be formed in a manner shownfor the lever system A.

FIG. 12 shows the lever system B with an arm 84 formed from the sheetmaterial with which this lever system engages the housing 48. The arm 84is received in a bore 85 formed in the housing 48 and is supported on adisc 86 with an end thereof formed as a blade.

' From FIGS. 3 and 4, it is apparent that both lever systems A and B'are stressed respectively by a bar spring SF. The force arm SF is fixedin the housing 48, while the other force arm SF engages the lever systemA and B at such an angle of inclination that a resultant is formed whichcauses the windings of the bar spring located between both force arms SFand SF to abut the housing 48 in each operative position of the leversystem.

A compression member 88 is articulatingly connected through the springs89 to the rounded heads of the lever systems A and B. The compressionmember 88 can be held at the levers also through the springs SF. Iclaim: I

1. Friction clutch comprising a housing, a pair of torque-transmittingfriction discs disposed in said housing, a respective pressure platelocated adjacent each of said friction discs, lever means operativelyconnected to said pressure plates said lever means comprising respectivelever systems for each of said pressure plates, said lever systems beingactuable substantially in parallel by a common member movable in anaxial direction of the clutch for lifting both of said pressure plates,said lever means being adapted to effect a substantially simultaneouslyinstituted, oppositely directed displacement of said pressure plates,said common member being an annular compression member, and at least oneof said lever systems has levers formed with support locations at theends thereof, said compression member being resiliently biased intoengagement with said support locations, said pressure plates havingfriction surfaces facing away from one another and being formed withannular seats on respective surfaces thereof facing toward one another,a plate spring disposed between said pressure plates and engaging saidannular seats, said housing being securable to a flywheel and beingformed with a reaction surface engageable by one of said friction discs,the flywheel having a reaction surface engageable by the other of said)friction discs, and means for rotationally entraining said pressureplates, both of said friction discs having respective hubs mountable ona single driven member for transmitting torque thereto.

2. Friction clutch according to claim 1 including a disengaging memberconnected to one of said pressure plates, and spring means forresiliently biasing said compression member into engagement with saidsupport locations, said spring means simultaneously serving as holderfor said compression member and as a force-locking application of saidone lever system to said disengaging member.

3. Friction clutch comprising a housing, a pair of torque-transmittingfriction discs disposed in said housing, a respective pressure platelocated adjacent each of said friction discs, lever means operativelyconnected to said pressure plates, a common member being movable toactuate said lever means for displacing said pressure platessubstantially simultaneously in axial direction of the clutch, saidpressure plates having friction surfaces facingaway from one another andbeing formed with annular seats on respective surfaces thereof facingtoward one another, a plate spring disposed between said pressure platesand engaging said annular seats, said housing being securable to aflywheel and being formed with a reaction surface engageable by one ofsaid friction discs, the flywheel having a reaction surface engageableby the other of said friction discs, and means for rotationallyentraining said pressure plates, said means for rotationally entrainingsaid pressure plates comprising leaf spring members securable, on theone hand, to said pressure plates and, on the other hand, to at leastone of said housing and said flywheel, said leaf springs being securedat their inner radial end portion to said pressure plates, both of saidfriction discs having respective hubs mountable on a single drivenmember for transmitting torque thereto.

4. Friction clutch according to claim 3 wherein said leaf spring membersare formed of U-shaped loops,

5. Friction clutch according to claim 3 wherein said leaf spring membersare attached at given points to said pressure plates, on the one hand,and to at least one of said housing and said flywheel, on the otherhand, said leaf spring members extending at various angles from thepoints of attachment to at least one of said housing and said flywheel.

6. Friction clutch according to claim 5 wherein the points of attachmenton said pressure plates are staggered radially.

7. Friction clutch according to claim 5 wherein the points of attachmenton said pressure plates are staggered circumferentially.

8. Friction clutch comprising a housing, a pair of torque-transmittingfriction discs disposed in said housing, a respective pressure platelocated adjacent each of said friction discs, lever means operativelyconnected to said pressure plates, said lever means comprisingrespective lever systems for each of said pressure plates, said leversystems being actuable substantially in parallel by a common member forlifting both of said pressure plates, said lever means being adapted toeffect a substantially simultaneously instituted, oppositely directeddisplacement of said pressure plates, said common member being anannular compression member, and at least one of said lever systems haslevers formed with support locations at the ends thereof, saidcompression member having a side thereof facing said levers of said onelever system and formed with profiled sections, said compression memberbeing resiliently biased so that said profile section on saidcompression member are resiliently biased into engagement with saidsupport locations, and means for rotationally entraining said pressureplates, both of said friction discs having respective hubs mountable ona single driven member for transmitting torque thereto.

1. Friction clutch comprising a housing, a pair of torquetransmittingfriction discs disposed in said housing, a respective pressure platelocated adjacent each of said friction discs, lever means operativelyconnected to said pressure plates said lever means comprising respectivelever systems for each of said pressure plates, said lever systems beingactuable substantially in parallel by a common member movable in anaxial direction of the clutch for lifting both of said pressure plates,said lever means being adapted to effect a substantially simultaneouslyinstituted, oppositely directed displacement of said pressure plates,said common member being an annular compression member, and at least oneof said lever systems has levers formed with support Locations at theends thereof, said compression member being resiliently biased intoengagement with said support locations, said pressure plates havingfriction surfaces facing away from one another and being formed withannular seats on respective surfaces thereof facing toward one another,a plate spring disposed between said pressure plates and engaging saidannular seats, said housing being securable to a flywheel and beingformed with a reaction surface engageable by one of said friction discs,the flywheel having a reaction surface engageable by the other of saidfriction discs, and means for rotationally entraining said pressureplates, both of said friction discs having respective hubs mountable ona single driven member for transmitting torque thereto.
 2. Frictionclutch according to claim 1 including a disengaging member connected toone of said pressure plates, and spring means for resiliently biasingsaid compression member into engagement with said support locations,said spring means simultaneously serving as holder for said compressionmember and as a force-locking application of said one lever system tosaid disengaging member.
 3. Friction clutch comprising a housing, a pairof torque-transmitting friction discs disposed in said housing, arespective pressure plate located adjacent each of said friction discs,lever means operatively connected to said pressure plates, a commonmember being movable to actuate said lever means for displacing saidpressure plates substantially simultaneously in axial direction of theclutch, said pressure plates having friction surfaces facing away fromone another and being formed with annular seats on respective surfacesthereof facing toward one another, a plate spring disposed between saidpressure plates and engaging said annular seats, said housing beingsecurable to a flywheel and being formed with a reaction surfaceengageable by one of said friction discs, the flywheel having a reactionsurface engageable by the other of said friction discs, and means forrotationally entraining said pressure plates, said means forrotationally entraining said pressure plates comprising leaf springmembers securable, on the one hand, to said pressure plates and, on theother hand, to at least one of said housing and said flywheel, said leafsprings being secured at their inner radial end portion to said pressureplates, both of said friction discs having respective hubs mountable ona single driven member for transmitting torque thereto.
 4. Frictionclutch according to claim 3 wherein said leaf spring members are formedof U-shaped loops.
 5. Friction clutch according to claim 3 wherein saidleaf spring members are attached at given points to said pressureplates, on the one hand, and to at least one of said housing and saidflywheel, on the other hand, said leaf spring members extending atvarious angles from the points of attachment to at least one of saidhousing and said flywheel.
 6. Friction clutch according to claim 5wherein the points of attachment on said pressure plates are staggeredradially.
 7. Friction clutch according to claim 5 wherein the points ofattachment on said pressure plates are staggered circumferentially. 8.Friction clutch comprising a housing, a pair of torque-transmittingfriction discs disposed in said housing, a respective pressure platelocated adjacent each of said friction discs, lever means operativelyconnected to said pressure plates, said lever means comprisingrespective lever systems for each of said pressure plates, said leversystems being actuable substantially in parallel by a common member forlifting both of said pressure plates, said lever means being adapted toeffect a substantially simultaneously instituted, oppositely directeddisplacement of said pressure plates, said common member being anannular compression member, and at least one of said lever systems haslevers formed with support locations at the ends thereof, saidcompression member having a side thereof Facing said levers of said onelever system and formed with profiled sections, said compression memberbeing resiliently biased so that said profile section on saidcompression member are resiliently biased into engagement with saidsupport locations, and means for rotationally entraining said pressureplates, both of said friction discs having respective hubs mountable ona single driven member for transmitting torque thereto.